Female Protein Research Articles

Annual reproductive phase-related profile of sex steroids and their carrier, SHBG, in the Indian major carp, Labeo rohita

This study reports annual cyclic changes in the plasma levels of sex hormone binding globulin (SHBG), sex steroids (E 2, estradiol; T, testosterone; P, progesterone) and protein (PRT) in correlation with reproductive phases in both sexes of an Indian major carp, Labeo rohita. Plasma SHBG, E 2, T and PRT levels in females and SHBG and T levels in males showed steady increases ( p < 0.005) in parallel with the gonadosomatic index (GSI) escalation in the preparatory and prespawning phases attaining peak levels before spawning. During the late spawning and early postspawning phases, E 2, T and SHBG levels revealed an abrupt and significant descent coincident with the GSI in both the sexes. The plasma P levels in females, attaining measurable quantities only in prespawning phase, underwent a rapid increase followed by a quick decline to undetectable levels in the spawning phase. This occurrence of P for a short duration suggests a limited role in ovarian function. During the resting phase, the E 2, T and SHBG levels in both sexes declined to minimum in conjunction with a decrease in the GSI, while PRT showed an increase. These data suggest that a significant increase in SHBG ( p < 0.005) prior to spawning enhances its binding capacity with sex steroids in both sexes synchronizing the reproductive activity. The significant increase of PRT in females during early spawning reflects its role in oocyte function, while PRT and E 2 in males may not significantly affect the testicular activity.

Schistosoma-induced amyloidosis in hamsters is gender-dependent

A high serum level of female protein (FP), found to be a constituent of Syrian hamster amyloid was associated with enhanced amyloidosis. In this work, we studied the sex-limited factors in the induction of amyloidosis in Syrian hamsters infected with either Schistosoma mansoni or S. hematobium cercariae. Hamsters were infected with different species of schistosome cercariae and sacrificed after different time periods of infection. Kidney and liver specimens were processed in paraffin, stained with Congo-red and examined by ordinary light and polarized light microscopy. Statistical analysis showed a significant difference in intensity of kidney and liver amyloid deposits (P<0.002 & <0.007 respectively) between females and male hamsters with extensive deposits in the former. Amyloid deposits were correlated significantly to the duration of infection (P<0.001) than the load of worm recovered. From this study, we conclude that, in hamster model, Schistosoma-induced amyloidosis is enhanced in females than male hamsters. This may be due to the high serum level of FP that is normally detected in females. As an experimental model for schistosomal nephropathy, we recommend to use male hamsters instead of females to minimize the effect of amyloid deposits, which may mask other pathological changes associated with schistosomal infection.

Female protein, amyloidosis, and hormonal carcinogenesis in Turkish hamster: differences from Syrian hamster.

The Syrian hamster (Mesocricetus auratus) has been widely used as an experimental animal and is a unique model for three sex hormone-regulated events: 1) estrogen-initiated renal carcinogenesis, 2) sex-limited expression of amyloidosis, a ubiquitous disease, and 3) sex hormone control of a serum amyloid P component (SAP) called female protein (FP). In this study, we evaluated the closely related Turkish hamster (Mesocricetus brandti) for these three events and found some very different responses: 1) estrogen-initiated renal carcinogenesis was not found in Turkish hamster, 2) amyloidosis was not sex limited and actually was a rare disease in the Turkish hamster, and 3) Turkish hamsters did express a sex-limited SAP-FP in serum that was antigenically identical and structurally very similar (97.5%) to Syrian hamster SAP-FP. However, acute phase regulation of SAP-FP synthesis was different, and serum levels of this pentraxin were much lower than those found in the Syrian hamster. On the other hand, in contrast to findings in the Syrian hamster, hepatic tumors were relatively common in normal and especially in estrogen-treated Turkish hamsters. Therefore, although they are closely related, these two Mesocricetus hamster species have markedly dissimilar responses to sex hormones.

Association of Rat C-Reactive Protein and Other Pentraxins with Rat Lipoproteins Containing Apolipoproteins E and A1

C-Reactive protein (CRP) is a member of the pentraxin family of proteins, ubiquitous components of animal serum. This study suggests that, in serum, rat CRP is complexed with lipoprotein and may interact directly with apolipoprotein E. When mixed with diluted rat serum, radiolabeled rat CRP showed a slightly higher sedimentation coefficient (about 15%) than that of the free protein. Elimination of calcium or addition of O-phosphorylethanolamine (O-PE), a low molecular weight compound that binds tightly to rat CRP in a calcium-dependent manner, abolished this difference. Adsorption of rat serum on a rat CRP affinity gel and elution with PE resulted in the isolation of material containing high levels of apolipoproteins E and A1. The affinity-purified preparation interacted with rat CRP and altered the sedimentation coefficient of the latter to the value observed in whole serum. Conversely, rat CRP increased the sedimentation coefficient of the major component of the affinity-purified material or to diluted rat serum, human serum amyloid P (SAP) and hamster female protein (FP), two other members of the pentraxin protein family, also had slightly higher sedimentation coefficients. In contrast, human CRP showed no evidence of an interaction in rat serum or with the affinity-purified proteins. This selectivity coincided with the ability of these pentraxins to bind to O-PE with high affinity. The sedimentation properties of serum lipoproteins, radiolabeled with [3H]cholesterol, also suggested an interaction with rat CRP.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum amyloid P (female protein) of the Syrian hamster. Gene structure and expression.

The structure and expression of the gene encoding serum amyloid P (SAP) component of the Syrian hamster have been studied by isolation of cosmid clones, nucleotide sequence analyses, and quantitation of nuclear run-on transcripts, nuclear RNA, mRNA, and protein levels. Hamster SAP, originally identified as female protein (FP), is a unique pentraxin because pretranslational expression of this gene is modulated by mediators of inflammation and sex steroids. SAP(FP) levels are high in sera from female hamsters and low in males. The response to inflammation is divergent; SAP(FP) levels decrease in females and increase in males during an acute phase response. The SAP(FP) gene encodes a 211 amino acid residue mature polypeptide as well as a 22-residue signal peptide. The intron/exon organization is similar to that of other pentraxins, but additional transcripts are generated from alternate polyadenylation sites in the 3' region. Circulating levels of SAP(FP) and the corresponding hepatic transcript levels are augmented by estrogen, while testosterone, dexamethasone, and progesterone cause a decrease in these levels. In addition the cytokines interleukin-1, -6, and tumor necrosis factor mediate a decrease in hepatic SAP(FP) transcript levels in female hamsters but did not cause a significant elevation of SAP(FP) mRNA in livers of male hamsters. The differences in expression of the SAP(FP) gene between male and female hamsters and between unstimulated male hamsters and male hamsters stimulated with an injection of lipopolysaccharide are due, at least in part, to alterations in transcription.

Hamster female protein binding to chromatin, histones and DNA

Hamster female protein (FP) is a member of the family of proteins known as pentraxins which share amino acid sequence homology, cyclic pentameric structure and calcium-dependent binding to ligands. Other members of this family include C-reactive protein (CRP) and serum amyloid P component (SAP), and most species synthesize both CRP and SAP. FP is unusual in that it is apparently the only pentraxin produced in hamsters, it is under hormonal control and it shares binding characteristics with both CRP and SAP. CRP has been defined and isolated by its calcium-dependent binding to pneumococcal C-polysaccharide via phosphocholine (PC) residues. SAP has been isolated by calcium-dependent binding to agarose. FP binds to both PC and agarose. Recently, both SAP and CRP have been found to bind to chromatin in a calcium-dependent manner and involvement of these proteins in the clearance of nuclear material has been proposed. In this paper we test whether FP shares the ability to bind to chromatin and histones, and compare its relative avidities for these ligands. Similar to CRP, FP bound to histones H1 and H2A, and chromatin. FP shared with SAP the ability to bind to DNA. However, FP binding was inhibited by PC for all ligands, whereas SAP binding was not. FP and SAP also failed to compete with each other for binding to DNA. By cross-inhibition FP bound much less well to PC than CRP, but was a very effective inhibitor of CRP binding to H2A. These studies demonstrate that chromatin and histone binding are conserved among these pentraxins. The role of the proposed PC binding site in these binding reactions is discussed.

Pentraxin family of proteins interact specifically with phosphorylcholine and/or phosphorylethanolamine.

Pentraxins are a family of serum proteins characterized by five identical subunits that are noncovalently linked. The two major types of pentraxins are C-reactive protein (CRP) and serum amyloid P component (SAP). CRP proteins are identified by their calcium-dependent interaction with phosphorylcholine. This study showed that SAP also bound to phosphorylated compounds but had a high specificity for phosphorylethanolamine. Thus, human CRP and SAP show high specificity that is complementary for the related compounds, phosphorylcholine and phosphorylethanolamine, respectively. This relationship suggests a complementary and/or related function for the pentraxins. Pentraxins from other species were also examined. Mouse SAP showed binding interactions and specificity similar to human SAP. Female protein (FP) from hamster and rat CRP showed a hybrid specificity and bound to both phosphorylethanolamine and phosphorylcholine. All of the proteins that bound phosphorylethanolamine also associated with human C4b-binding protein (C4BP). With the exception of human and rat CRP, all the proteins also bound to vesicles containing acidic phospholipids. All of these binding interactions were calcium-dependent and mutually exclusive, suggesting that they involved the same site on the protein. These findings suggest possible ways to examine the function of the pentraxins.

The rat female protein, a pentraxin with lectinic properties

The C-reactive protein is the major acute phase protein (APP) in humans which binds lectin-like to different membraneous structures and exerts an important function in non-specific defense. Because of a pentameric molecular symmetry CRP as well as serum amyloid P component (SAP) and hamster female protein (FP) was merged into a special protein family named pentraxins. In rats a protein was found referred to as rat FP which was close related to hamster FP with respect to hormonal regulation and APP nature as well. Based on this conformity the molecular structure of rat FP was analyzed and as the results a pentameric structure could be demonstrated for rat FP, too. Furthermore, the response of rat CRP and FP on injection of adrenal hormones, agents being involved in acute phase reaction, was investigated. Epinephrine administration led to an increase in CRP and a decrease in FP serum concentration. Dexamethasone has the same effect in case of FP and changed the CRP concentration in a biphasic way with a maximum at about 0.01 mg/kg, a minimum at 0.6 mg/kg and a return to control values at 1.8 mg/kg. Thus, the results indicate a neuroendocrine control of CRP and FP but probably in a different way. Using FITC-labelled lectin the exposition of galactose-containing membraneous structures could be demonstrated in carbon tetrachloride-injured liver tissue in contrast to controls. These binding sites are in accordance with increased FP-binding shown by immunofluorescence histochemistry. Thus, lectin-like properties may be ascribed to rat FP comparable to CRP and SAP activity. The results are discussed with respect to findings from literature that also the acetylcholine receptor seems to have a pentameric structure.

C-reactive protein (CRP) of the syrian hamster

Complementary and genomic clones encoding the mRNA and gene for a protein in the Syrian hamster that is highly homologous to C-reactive protein (CRP) have been isolated and studied. Coding sequence of the genomic clone is identical with that of the cDNA clone and predicts a mature protein of 206 amino acids and a 19 amino acid signal peptide. The single intron is 217 base pairs long and contains a short repetitive (GT)n motif. RNA blot analysis demonstrates that mRNA for hamster CRP is approximately 2.0 kb long, and unlike the closely related pentraxin female protein (FP), expression of this mRNA is not affected by the gender of the animal and accumulates equally in males and females during inflammation. In vivo administration of interleukin 1, interleukin 6, and tumor necrosis factor induces accumulation of hepatic CRP mRNA, and the acute-phase alterations in CRP mRNA levels arise as a result of enhanced gene transcription.

Armenian hamster female protein: a pentraxin under complex regulation

The serum of Armenian hamster (Cricetulus migratorius) contains a protein homologous to female protein (FP) that has been characterized in the Syrian (golden) hamster. Of unknown function, FP belongs to a family of proteins (called pentraxins) that have a common ancestral gene and are widely expressed in nature. Whereas serum concentration of FP in Syrian hamsters (SFP) is many fold greater (200- to 300-fold) in females vs. males, Armenian hamster FP (AFP) is only moderately elevated (approximately 3-fold) in female vs. males and only for the fall-winter months of the year. In the Armenian hamster testosterone administration to females or castration of males has no effect on AFP serum levels, whereas in Syrian hamster these treatments change SFP serum concentration to that characteristic of the opposite sex. Some sex steroid control of hepatic AFP synthesis is evident, however, as serum levels decrease after exogenous estrogen treatment. In contrast to Syrian hamster FP, normal levels of AFP are dependent on an intact hypophysial-pituitary axis and also are influenced by the season of the year. As an acute-phase protein, AFP responds in a typical fashion, with increasing serum levels detected in both sexes in contrast to the divergent sex-limited response in Syrian hamsters. Although AFP and SFP are similar structurally, morphologically, and antigenetically and share common binding specificities, the regulation of FP synthesis in Armenian hamster is very different from that previously found in Syrian hamster.

Armenian hamster female protein (serum amyloid P component). Comparison with the sex-regulated homolog in Syrian hamster.

Complementary DNA clones for Armenian hamster female protein (FP) were isolated and the complete nucleotide sequence and derived amino acid sequence were determined and compared with relevant data for the closely related Syrian hamster. Although biosynthesis of preSAP is directed by a 1.0-kb mRNA in both genera and the molecular mass of the primary translation product of FP is identical, the FP gene structure and regulation of expression of FP are different in Syrian and Armenian hamsters. Whereas the direction of alteration in FP mRNA levels is divergent in Syrian hamsters during an acute phase reaction, hepatic FP mRNA levels increase in both male and female Armenian hamsters during inflammation. Regulation of expression of Armenian and Syrian hamster FP genes occurs at a pretranslational level.

Tamoxifen inhibits estrogen-induced hepatic injury in hamsters.

Estrogens have an unusual toxic effect on the liver of two hamster species, the Armenian and the Chinese hamster. The hepatotoxicity was detectable clinically by hyperbilirubinemia and confirmed histologically by the presence of hepatic degenerative-regenerative changes. Administration of tamoxifen with estrogen [either ethynyl estradiol or diethylstilbestrol (DES)] completely abrogated the hepatotoxic effects, suggesting that estrogen receptor (ER) was necessary for estrogen to damage liver. In Armenian hamsters, estrogens decreased hepatic synthesis of female protein (FP); tamoxifen also abolished this DES effect and resulted in a net increase in serum FP levels. DES administration produced higher serum bilirubin levels and lower serum FP levels in females than in males. Paradoxically, tamoxifen blocked these DES effects more effectively and efficiently in females than in males. Estrogens did not injure uteri of Armenian and Chinese hamsters and were nontoxic to livers of other hamsters species, such as Syrian and Turkish. This model provides another perspective of the acute cellular derangement that can be effected by estrogen-ER complex and may indicate a yet unknown mode of ER action.

Regulation of the antibody response by the acute phase reactant: Mouse serum amyloid P-component (SAP)

Serum amyloid P-component (SAP) is the major acute phase reactant (APR) of mice. Purified mouse SAP at 0.1 to 10.0 μg/ml selectively suppressed the secondary in vitro IgG antibody plaque-forming cell (PFC) response to the T-dependent antigen TNP-KLH but not to the T-independent antigens TNP-LPS and DNP-Lys-Ficoll. The suppression was antigen nonspecific. The mechanism of suppression occurred primarily through the activation of Lyt-1 +, I-J + suppressor-inducer cells, which in turn activated a Lyt-2 + suppressor T-cell population. The activity of preexisting, antigen-specific Lyt-2 + suppressor T cells was not influenced by SAP. The antigen-nonspecific suppressor T cells generated by SAP were sensitive to cyclophosphamide. Removal of SAP from the culture fluid with rabbit anti-Mo SAP antibody or agarose beads abrogated the suppression. Pentraxin proteins closely related to mouse SAP, such as human SAP and hamster female protein (FP), also displayed immunoregulatory activity of the antibody response by the same cellular mechanism. The results suggest that SAP regulates antibody responses by the activation of suppressor-inducer T cells and that the regulation of the antibody response during the acute stage of inflammation may occur via SAP.

Hamster female protein, a pentameric oligomer capable of reassociation and hybrid formation

Syrian hamster female protein (SFP), a serum oligomer composed of five identical subunits, was reassociated in vitro from monomer subunits. The reconstituted pentamer was genuine by morphologic, antigenic, and structural criteria. Another female protein (FP), a homologue from Armenian hamsters (AFP), also reassociated into a pentamer after dissociation with 5 M guanidine hydrochloride. These two FP's hybridized when a mixture of them was dissociated and then reassociated. Differences between the parent FP's were used to show that the recombinant pentamer contained monomer subunits from both SFP and AFP. Reassociation of both FP's was enhanced by increasing FP concentration and also by adding Ca2+ during reassembly. The two FP's differed in their reassociation profile in that SFP was especially efficient in reassembly, whereas AFP was more dependent upon Ca2+. Female protein is a homologue of C-reactive protein and amyloid P component, and all of these proteins (pentraxins) share a similar structure. The in vitro dissociation-reassociation of female protein described herein may reflect an in vivo dissociation-reassociation which is functionally important and a common metabolic feature within this family of proteins.

Complement Activation by Female Protein, the Hamster Homologue of Human C-Reactive Protein

The capacity of Syrian hamster female protein (FP), a phosphorylcholine (PC)-binding pentraxin, to activate complement was tested in an in vitro system consisting of PC-coupled sheep red blood cells and guinea pig serum as the complement (C) source. FP was demonstrated to fix complement as reflected by hemolysis. Such hemolysis was eliminated by heat treatment (56 degrees C, 30 min) of guinea pig serum and inhibited by PC chloride but not dinitrophenyl lysine. The inability of C4-deficient guinea pig serum to provide lytic activity indicated that lysis proceeded through the classical hemolytic pathway.

Hamster female protein, a sex-limited pentraxin, is a constituent of Syrian hamster amyloid.

Female protein (FP) is a pentraxin of Syrian hamster which is a homologue of two human pentraxins, C-reaction protein (CRP) and amyloid P component (AP). Functionally, FP has been shown to be similar to CRP, although FP has more homology at the amino terminus with AP. The present work investigated amyloid in the Syrian hamster to determine whether FP was involved in a manner analogous to AP. FP was found to be a constituent of Syrian hamster amyloid. This conclusion was based on the following results: (a) FP was consistently detected in amyloid deposits by fluorescent microscopy with specific antisera; (b) The amount of FP extractable from hamster livers directly correlated with the presence of amyloid; and (c) 125I-FP injected intravenously into amyloidotic hamsters rapidly left the intravascular compartment and was found subsequently in amyloid deposits. This unusual alteration of plasma metabolism and amyloid localization of 125I-FP was a characteristic finding in amyloidotic hamsters and was specific for 125I-FP. Therefore, as an amyloid component, FP appears to be functionally similar to human AP. However, FP synthesis is under sex steroid control and the unique sex-limited expression of this pentraxin was associated with an equally novel propensity for deposition of amyloid in female hamsters under normal or experimental conditions. Thus, a high serum level of FP, as found in normal females or diethylstilbestrol-treated males, was associated with enhanced amyloidosis. Although speculative at present, a primary role for serum FP in hamster amyloid deposition may be experimentally approachable by hormonal manipulation of FP synthesis.

Syrian Hamster Female Protein: Analysis of Female Protein Primary Structure and Gene Expression

The concentration in plasma of the female protein (FP) of the golden Syrian hamster is regulated by sex steroids and by mediators of the acute-phase response to tissue injury or inflammation. A complementary DNA (cDNA) clone corresponding to FP was isolated from a hamster liver cDNA library and used to determine the nucleotide sequence and derived amino acid sequence of native FP. The primary sequence of FP is 69 percent identical to human serum amyloid P component and 50 percent identical to human C-reactive protein. Evidence showed that sex-limited and acute-phase control of the FP gene is pretranslational. The FP protein is thus a useful model for investigating dual regulation of expression of a single gene.

Hamster female protein. A divergent acute phase protein in male and female Syrian hamsters.

Normal adult male hamsters have low levels (10-20 micrograms) of female protein (FP) in serum which increase approximately fivefold during an acute phase response. In contrast, normal females have 50- to 100-fold higher serum levels and the acute phase reaction consists of a transient decrease in FP (approximately 50%), followed by a return to normal levels even under adverse conditions such as cortisone treatment (which by itself has a depressing effect on FP levels in normal females). The acute phase response was not inherently associated with gender, as the pattern of response could be changed to that of the opposite sex by appropriate hormonal manipulation. That is, castrated or diethylstilbestrol-treated males with high FP levels showed a female-type response whereas testosterone-treated females with low FP levels showed a male-type response. Studies on catabolism of 125I-FP showed a similar rapid half-life (T1/2, 9-16 h) in normal males and females and indicated that the sex difference in serum concentration was due to greater synthesis of FP in females. The divergent acute phase reaction of serum FP was related directly to changes in the FP synthetic rate (increased in males, decreased in females). As an indicator of serious pathology, a decrease of FP to very low levels in females was associated frequently with impending death.

Hamster female protein. A new Pentraxin structurally and functionally similar to C-reactive protein and amyloid P component.

Female protein (FP), a serum protein present in normal female hamsters was found to be similar to acute-phase reactant, C-reactive protein (CRP) and serum amyloid P component (SAP) in the following ways: (a) hamster FP complexed with phosphorylcholine (PC) in a Ca++-dependent fashion as shown by its isolation from serum by affinity chromatography with PC-Sepharose and selective elution with free PC or EDTA; (b) electron microscopy of FP indicated a pentameric structure similar in size and appearance to other pentraxins; (c) the parent molecule of FP (150,000 mol wt) was composed of five noncovalantly assembled subunits of 30,000 mol wt; and (d) the amino acid analysis and terminal NH2 sequence of FP clearly showed homology with SAP-CRP. Although FP evolved from an ancestral gene common to SAP and CRP, and shares functional, morphological and structural properties with these acute-phase proteins, the biological homology of FP appears quite diverse as this protein is a prominent serum constituent (1-2 mg/ml) of normal female hamsters and under hormonal control (testosterone suppression) in males.

A sex-limited serum protein of Syrian hamsters: definition of female protein and regulation by testosterone.

Normal Syrian hamster females contain a serum protein not found by simple gel diffusion assay in normal adult males. This sex-limited protein was called female protein (FP). Low levels of FP were found in sera from normal weanling male hamsters. Adult male hamsters castrated or treated with diethylstilbestrol also developed serum FP, which could be suppressed by administration of testosterone. Exogenous testosterone also suppressed serum FP in adult females, and ovarian function did not appear to be critical for maintenance of serum FP. Although FP is present in significant amounts (1-2 mg/ml) in adult females, its function is presently unknown.